Typical Easily made motor bike

[5-7HEAVEN]

i may be wrong, but here goes:
first, ya need to research as mch as you can learn about your engine, to see what rpm your powerband will be. if you bought an engine kit, the manufacturers have done most of your research/homework for you.then you need to research and calculate how fast you want to go and at what rpm. use the diameter of your back wheel to calculate out what your sprockets' sizes should be. if your engine sprocket is 10 teeth with no reduction gear on the engine, your rear sprocket MIGHT be 100teeth, and 18" in diameter.
after doing research and interference measurements, then you can mount the engine. with reduction gear or a CVT transmission, the size of the rear sprocket will decrease. if it's a straight shot to the rear sprocket without hitting the frame/fender/tire, then you choose the rear sprocket and chain that will work with the front sprocket, and is the correct gear ratio to keep the engine within its powerband.
don't worry about the size of the chain...yet. who knows, ya might end up routing the drive onto your bike's 21-speed gears.

 

[Earth Mechanic]

Dude, go to a bike store and look on the box. Or call them.

 

[MisterSteve124]

I got my bike 2 years ago and it didn't come in a box. And 5-7 Heaven I am routing the drive onto the bikes gears. Which is why I am trying to figure out what size chain it's using. So that I can get a clutch with a sprocket the will fit.

 

[azbill]

it depends on the back wheels gearing
single speeds are generally 35 chain
multi-speed casettes take a narrower chain

 

[MisterSteve124]

Ok but do you know any way I can tell? If I take a picture of the sprockets or the chain or something?

 

[azbill]

just for kicks posted this link to a good chart. http://www.azusaeng.com/chain/mcyclchn.html
or search for chain chart i have a caliper but no longer have my original chain. i use a "41" its the same pitch and same roller size but is 1/16th inch wider. my kit came with the 415 chain.

try the link and see if it helps you

 

[MisterSteve124]

Ok I did some research and it said that bikes use #40 size chain. And I double checked it to make sure that it had 1/2" pitch.

 

[bamabikeguy]

I believe I remember that "chain thread", that the chain was purchased at an agricultural supply co-op, used in augers/feeders and such... and I'm thinking it was #.415.

 

[MisterSteve124]

What does that have to do with this?

 

[bamabikeguy]

http://www.motoredbikes.com/showthread.php?t=4674&highlight=chain+.415+farm

Well, since the old links don't work, was just hinting that if you searched on "farm" and ".415," a link would probably pop up.

It was called Good Karma/bad Karma , not much of a lead.....